vowels = ['a', 'e', 'i', 'o', 'u']
word = "Milliways"
for letter in word:
    if letter in vowels:
        print(letter)

found = []
len(found)
# 用append增加对象
found.append('a')
found.append('e')
found.append('i')
found.append('0')
len(found)

# 用"in"检查成员关系：使用In操作符检查一个对象是否包含在一个集合里，还可以使用not in操作符组合来检查一个集合是否不存在某个对象
if 'u' not in found:
    found.append('u')
found

# 原来的“vowels.py”,这个代码会显示“word”中找到的元音
vowels = ['a', 'e', 'i', 'o', 'u']
word = "Milliways"
for letter in word:
    if letter in vowels:
        print(letter)

vowels = ['a', 'e', 'i', 'o', 'u']
        word = "Milliways"
        found = []
        for letter in word:
            if letter in vowels:
                if letter not in found:
                    found.append(letter)
        for vowel in found:
            print(vowel)